Amazon was a pioneer in e-commerce. Moving well beyond the books it started with, the company built a strong business around the efficient sale and delivery of most any kind of packaged goods. For its second act, the company now seems intent on achieving nothing less than similar success with the sale of digitally delivered merchandise.

Today Amazon opened the doors on its own casual games portal. The online store, which is characterized as a Beta, is hosting more than 600 titles at launch. All are priced at $6.99 and $9.99 and available for immediate download. Each can be tested in thirty minute long demos and three free games are available initially as part of a promotion (available here through February 10).

Downloading games from the store does require customers first download a “helper” application that seems to play a role in authenticating the customer. It is a process similar to that used with Amazon’s other download services. In practice, it’s simple.

One restriction: as a beta, the downloads are currently limited to the PC (no Mac service yet). The portal is also limited to relatively small scale titles matched to Amazon’s broader retail demographic. More “core gamer,” AAA grade, or feature length games, from publishers like Electronic Arts or Activision aren’t included. It’s possible in the future this will change if the store takes off.

Competitively, Amazon will go against portals like Yahoo Games, EA’s Pogo and also, to a lesser extent, Valve’s broader game distribution platform Steam.

In this early incarnation, the Amazon offering seems something of a fish in an already crowded sea but given Amazon’s brand strength, the technical prowess of the company’s web services organization, the beta warrants watching as it grows.

Just as Amazon MP3 has grown into a significant digital music distributor, Amazon games could also become a significant outlet in the growing games marketplace.